Conventional dynamic load/unload-type disk drives typically include a base plate and a cover that is detachably connected to the base plate to define a housing for various disk drive components. One or more data storage disks are generally mounted on a spindle which is interconnected with the base plate and/or cover so as to allow the data storage disk(s) to rotate relative to both the base plate and cover via a spindle motor. An actuator arm assembly (e.g., a single rigid actuator arm, a plurality of rigid actuator arms, an E-block with a plurality of rigid actuator arm tips), is interconnected with the base plate and/or cover so as to allow the actuator arm assembly to move relative to both the base plate and cover in a controlled manner. This motion is either typically a pivoting or a linear motion.
A suspension or load beam may be provided for each data storage surface of each data storage disk. Typically each disk has two of such surfaces. All suspensions are appropriately attached to and extend away from the actuator arm assembly in the general direction of the data storage disk(s) during normal operations. A transducer, such as a read/write head, is carried by a slider that is disposed on the free end of each suspension. Signals are exchanged between the head and the corresponding data storage disk to read and/or write informnation. The position of the actuator arm assembly, and thereby cach transducer, is controlled by a voice coil motor or the like which moves the actuator arm assembly to dispose the head(s) at the desired radial position relative to the corresponding data storage disk.
The head(s) of the disk drive is parked off its corresponding data storage disk by using a load/unload ramp. The load/unload ramp is typically disposed at least toward (and possibly beyond) the perimeter of the corresponding data storage disk. Load/unload ramps may be made from plastic to reduce material costs, and are nonetheless attached to the base plate. It is desirable to have the load/unload ramp demonstrate good wear characteristics as the suspension/slider moves along the ramp. Moreover, it is desirable for the load/unload ramp to tolerate the increased temperatures that exist within the disk drive housing during disk drive operations. Certain plastics may have a tendency to creep at these temperatures, particularly over those areas of the load/unload ramp that are stressed by the attachment of the load/unload ramp to the base plate.“Creeping” refers to a progressive deformation over a period of time due to a material being under a constant load or stress. This time dependent deformation has proven to be a limiting factor in the operational integrity of at least certain designs of load/unload ramps that are formed from plastic.
Creeping of a plastic load/unload ramp may have a number of undesired effects. For example, if the plastic load/unload ramp is attached to the base plate using a screw, over time, creeping of the ramp plastic may loosen the screw and result in the screw failing to adequately secure the load/unload ramp to the base plate. This problem has been addressed in a number of ways. A common practice to combat creeping has included insert-molding a metal plate into the plastic load/unload ramp to increase the integrity of the attachment of the ramp to the base plate. However, this addition of a metal plate to the load/unload ramp can more than double the cost of producing such ramps. Another attempt at solving the problem of creeping reflects using a screw in combination with locking devices to attach the plastic load/unload ramp to the base plate. However, locking devices such as thread locks not only add cost, but also add the risk of outgassing (i.e., the vaporization of materials from one or more surfaces of the thread locks after they are placed in low pressure environments during disk drive operations). Further, locking devices such as lock-washers add cost, create particulates, and may require a more expensive grade of ramp plastic for compatible use. While suitable plastics with improved creep characteristics are known, they are significantly more expensive than even the attempted improved attachment methods. Therefore, it would be desirable to have a load/unload ramp of a configuration that reduces manufacturing costs, provides a use-life that is greater than that of conventional ramps, and/or that reduces the effect of creep in relation to the attachment of the load/unload ramp to the base plate.